Worktable that is extendible in two steps

ABSTRACT

A worktable includes two first rails arranged in parallel on a base, two guide rods movable along the first rails in a first direction and a second direction reversed to the first direction, two second rails respectively slidably coupled to the guide rods, a sliding plate fixedly mounted on the second rails, and a positioning device for locking the sliding plate to stop the sliding plate from movement relative to the base.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a divisional application of pending U.S. applicationSer. No. 11/149,354, filed Jun. 10, 2005, now U.S. Pat. No. 7,240,706(of which the entire disclosure is hereby incorporated by reference).

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a work platform for a sawing machineand more particularly, to a worktable that is extendible in two steps.

2. Description of the Related Art

FIGS. 1-3 show a platform assembly for attaching to an objectconstructed according to U.S. Pat. No. 6,619,348. The platform assembly1 comprises a base 2, two beams 3, two rails 4, a first end board 5, asecond end board 5′, four blocks 6, a plate 7, and two stops 8. Thebeams 3 are disposed in parallel on the top wall of the base 2, eachhaving a groove 3 a formed therein. The two rails 4 are respectivelyslidably received in the groove 3 a of each beam 3. The first and secondend boards 5 and 5′ respectively secured to the ends of the rails 4. Thefour blocks 6 are secured to the bottom wall of the plate 7 and coupledto the rails 4 to selectively engage with either of the end boards 5 and5′. The plate 7 is slidably supported on the rails 4. The two stops 8are disposed on the base 2 between the beams 3. FIG. 2 is a schematicdrawing showing the plate 7 moved leftwards. When two of the four blocks6 are moved with the plate 7 leftwards after contacting the first endboard 5, the two rails 4 will be moved together with the plate 7, andthe movement of the plate 7 will be stopped upon engagement of thesecond end board 5′ with the stops 8. At this time, the plate 7 is atthe left side of the base 2 as shown in FIG. 3.

According to the aforesaid design, the plate 7 is slidable relative tothe base 2 to extend the work area of the object supporting the platformassembly 1. In actual practice, this design of platform assembly 1 isstill not satisfactory in function. As shown in FIG. 2, when the plate 7is stopped after having been extended out, the plate 7 protrudes overthe base 2 at a distance. At this time, the plate 7 is partially coupledto and supported in the groove 3 a of each beam 3 through the rails 4.When the plate 7 carries a heavy object, the rails 4 may be forced tocurve or break due to excessive long arm of force.

Further, because the plate 7 and the two rails 4 are not lockable, theyslide freely within a range. More particularly after the plate 7 hasbeen extended out, it may be pushed back accidentally. This unexpectedretraction of the plate 7 makes trouble in the processing work.

Therefore, it is desirable to provide a worktable that eliminates theaforesaid drawbacks.

SUMMARY OF THE INVENTION

The present invention has been accomplished under the circumstances inview. It is one object of the present invention to provide a worktable,which has an extendible working surface and a stable supportingstructure.

To achieve this object of the present invention, the worktable comprisesa base having a top wall; at least one first rail fixedly mounted on thetop wall of the base, the at least one first rail each having a guidegroove, a first stop and a second stop; at least one guide rodrespectively received in the guide groove of each of the at least onefirst rail and alternatively movable in a first direction and a seconddirection reversed to the first direction, the at least one guide rodeach having a first end and a second end; a first end strip fixedlyfastened to the first end of each of the at least one guide rod forstopping the at least one guide rod from movement in the first directionwhen the first end strip touched the first stop of each of the at leastone first rail; a second end strip fixedly fastened to the second end ofeach of the at least one guide rod for stopping the at least one guiderod from movement in said second direction when the second end striptouched the second stop of each of the at least one first rail; asliding plate slidably supported on the at least one guide rod, thesliding plate having a bottom wall; and at least one second rail fixedlymounted on the bottom wall of the sliding plate, the at least one secondrail having a guide groove, which receives one of the at least one guiderod, a first push portion, which enables the at least one guide rod tobe moved in the first direction when touching the second end strip, anda second push portion, which enables the at least one guide rod to bemoved in the second direction when touching the first end strip.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an exploded view of an adjustable and extendible platformassembly for working table according to U.S. Pat. No. 6,619,348.

FIG. 2 is a sectional view of a part of FIG. 1.

FIG. 3 is a schematic drawing showing an application example of theadjustable and extendible platform assembly shown in FIG. 1.

FIG. 4 is an exploded view of a worktable according to a firstembodiment of the present invention.

FIG. 5 is top view of the worktable according to the first embodiment ofthe present invention.

FIG. 6 is a top view of the worktable corresponding to the positionshown in FIG. 5, showing the positioning rod locked the sliding plate.

FIG. 7 is a schematic bottom view of the worktable according to thefirst embodiment of the present invention.

FIG. 8 corresponds to FIG. 6, showing the positioning rod unlocked fromthe sliding plate.

FIG. 9 corresponds to FIG. 5, showing the sliding plate continuouslymoved in the first direction.

FIG. 10 a top view of the worktable corresponding to the position shownin FIG. 9, showing the positioning rod locked the sliding plate.

FIG. 11 corresponds to FIG. 9, showing the sliding plate continuouslymoved in the first direction.

FIG. 12 is a top view of the worktable corresponding to the positionshown in FIG. 11, showing the positioning rod locked the sliding plate.

FIG. 13 corresponds to FIG. 11, showing the sliding plate moved in thesecond direction.

FIG. 14 is a top view of the worktable corresponding to the positionshown in FIG. 13, showing the positioning of the sliding plate.

FIG. 15 is an exploded view of a worktable according to a secondembodiment of the present invention.

FIG. 16 is a top view of a worktable according to a third embodiment ofthe present invention, showing the sliding plate moved in the firstdirection.

FIG. 17 is a schematic drawing of the third embodiment of the presentinvention, showing the sliding plate moved in the second direction.

DETAILED DESCRIPTION OF THE INVENTION

Referring to FIGS. 4-7, a worktable 100 is shown attached to a sawmachine base 200. The worktable 100 comprises a base 10, two first rails16, two guide rods 20, a first end strip 24, a second end strip 26, asliding plate 28, two second rails 30, a positioning device 34, and alimiter 36.

The base 10 comprises a main platform 12 and a supplementary platform14. The main platform 12 comprises a working surface 121, a front fence122 and a left-side fence 123, an elongated slot 124 formed in the frontfence 122, three notches 125, 126 and 127 formed in the front fence 122in communication with the elongated slot 124, and a through hole 128formed in the left-side fence 123. The supplementary platform 14comprises a top wall 141 disposed at a relatively lower elevation thanthe working surface 121 and divided into a first connecting section 143and an open-space section 144 and a second connecting section 145, asidewall 142, and a through hole 146 formed in the sidewall 142corresponding to the through hole 128 in the left-side fence 123 of themain platform 12.

The two first rails 16 are respectively fixedly mounted on the firstconnecting section 143 and second connecting section 145 of thesupplementary platform 14, each having a guide groove 161, a first stop162 and a second stop 163. As shown in FIG. 4, each first rail 16 isformed of a first locating block 17 and a second locating block 18. Thefirst locating block 17 has a groove 171. The second locating block 18has a groove 181. The grooves 171 and 181 are axially connected in aline, thereby forming the guide groove 161. One side of the firstlocating block 17 forms the first stop 162 and one side of the secondlocating block 18 forms the second stop 163.

The two guide rods 20 each are comprised of a first rod body 21 and asecond rod body 22 arranged in parallel. The first rod body 21 of eachof the guide rods 20 is respectively received in the guide groove 161 ineach of the two first rails 16 so that the two guide rods 20 can bealternatively moved relative to the base 10 in a first direction D1 anda second direction D2 reversed to the first direction D1. Further, eachguide rod 20 has a first end 20 a and a second end 20 b.

The first end strip 24 is fixedly connected to the first end 20 a ofeach of the two guide rods 20. The second end strip 26 is fixedlyconnected to the second end 20 b of each of the two guide rods 20.Therefore, the two guide rods 20 form with the first end strip 24 andthe second end strip 26 a rectangular open frame. Further, the first endstrip 24 has a lug 241 at each of the two ends thereof, and the secondend strip 26 also has a lug 261 at each of the two ends thereof.

The sliding plate 28 comprises a planar plate body 281 and two sidestrips 282 and 283. The area of the sliding plate 28 is approximatelyequal to the top wall 141 of the supplementary platform 14.

The two second rails 30 are fixedly mounted on the bottom side of theplanar plate body 281 of the sliding plate 28, each having a guidegroove 301, a first push portion 302, and a second push portion 303. Asshown in FIGS. 4 and 6, each second rail 30 is formed of a first slidingblock 31 and a second sliding block 32. The first sliding block 31 has agroove 311 formed therein. The second sliding block 32 has a groove 321formed therein. The groove 311 and the groove 321 form the guide groove301 of the respective second rail 30. The guide groove 301 of eachsecond rail 30 receives the second rod body 22 of each of the two guiderods 20 respectively, enabling the sliding plate 28 to be slidablysupported on the two guide rods 20. Further, the first sliding block 31has one side forming the first push portion 302, and the second slidingblock 32 has one side forming the second push portion 303.

The positioning device 34 comprises three positioning holes 341, 342 and343 formed in one side strip 282 of the sliding plate 28, and apositioning rod 344 kept behind the front fence 122 of the main platform12 (see FIG. 6). The positioning rod 344 has a finger block 345projecting into the elongated slot 124 in the front fence 122 of themain platform 12 for pulling by the user with the fingers to move thepositioning rod 344 alternatively backwards and forwards in a lineardirection. When the finger block 345 is moved into one notch 125, 126 or127, the positioning rod 344 is stopped from movement.

The limiter 36 according to this embodiment is a screw bolt fastened tothe sidewall 142 of the supplementary platform 14, having a head 361 andan end 362. Through the head 361, the user can rotate the limiter 36 topress the end 362 against one guide rod 20.

After understanding of the component parts of the worktable 100 andtheir relative positions, the operation of the worktable 100 isdescribed hereinafter.

Referring to FIGS. 5 and 6, before pushing the sliding plate 28, thelugs 261 of the second end strip 26 are respectively abutted against thesecond stop 163 of the first rails 16 to prevent sliding of the slidingplate 28 in the second direction D2. The positioning rod 344 is insertedwith one end thereof into the through hole 128 in the left-side fence123 of the main platform 12, the positioning hole 341 and then thethrough hole 146 in the sidewall 142 of the supplementary platform 14.When the finger block 345 is moved into the notch 127, the positioningrod 344 prevents sliding of the sliding plate 28 in the first directionD1.

When wishing to push the sliding plate 28 out of the base 10 in order toincrease the working area of the worktable, push the positioning rod 344backwards, as shown in FIG. 8, to engage the finger block 345 into thenotch 125, preventing displacement of the positioning rod 344.Thereafter, as shown in FIG. 9, the sliding plate 28 is pushed in thefirst direction D1 to stop the first push portion 302 of each of thesecond rails 30 against the second end strip 26. At this time, we canmove the positioning rod 344 to selectively force the finger block 345into the notch 126, as shown in FIG. 10, so that one end of thepositioning rod 344 can be inserted into the positioning hole 342 tostop the sliding plate 28 in position. Alternatively, we can keep movingthe sliding plate 28, as shown in FIG. 11, thereby carrying the twoguide rods 20 to the position where each lug 241 of the first end strip24 is respectively stopped against the first stop 162 of thecorresponding first rail 16. At this time, one end of the positioningrod 344 can be inserted into the positioning hole 343 and the fingerblock 345 is engaged into the notch 126, as shown in FIG. 12, to stopthe sliding plate 28 from displacement. Further, under this condition,the sliding plate 28 effectively increases the workable area of theworktable 100. Because the sliding plate 28 does not protrude over thebase 10 to a far distance at this time, carrying a heavy object on thesliding plate 28 does not cause the two guide rods 20 to deform orbreak.

When the position of the sliding plate 28 is changed, one end of thepositioning rod 344 is properly inserted into one positioning hole 341,342 and 343 in one side strip 282 of the sliding plate 28 to hold thesliding plate 28 on the supplementary platform 14 firmly in position,preventing trouble and inconvenience due to displacement of the slidingplate 28 accidentally during working, and improving the safeness of theoperation of the machine.

Referring to FIGS. 13 and 14, when moving the sliding plate 28 in thesecond direction D2, the second push portion 303 of each of the secondrails 30 will be stopped against the first end strip 24, enabling thetwo guide rods 20 to be moved with the sliding plate 28 in the seconddirection D2 to the position where each lug 261 of the second end strip26 is stopped against the second stop 163 of the corresponding firstrail 16.

During the aforesaid operation, we can rotate the limiter 36 to forcethe end 362 against the respective guide rod 20, thereby holding downthe respective guide rod 20. Thus, the moving range of the sliding pate28 can be limited subject to a particular processing requirement.

FIG. 15 is an exploded view of the second embodiment of the presentinvention. According to this embodiment, the first rails 38 and thesecond rails 40 each are formed of one single solid bar. Each first rail38 has a groove 381 extending along the length, a first stop 382 at oneend, and a second stop 383 at the other end. Each second rail 40 has agroove 401 extending along the length, a first push portion 402 at oneend, and a second push portion 403 at the other end.

FIG. 16 is an exploded view of the third embodiment of the presentinvention. According to this embodiment, the first stop 421 and thesecond stop 422 which are respectively formed in the first locatingblock 43 and second locating block 44 of the same first rail 42 arearranged facing each other. This embodiment further comprises two stopblocks 48 respectively provided at the first rod body 461 of each of thetwo guide rods 46. Each stop block 48 has a first stop portion 481 atone side, and a second stop portion 482 at the opposite side. When thefirst stop portion 481 of one stop block 48 touches the first stop 421of the respective first rail 42, the guide rods 46 and the sliding plate50 are prohibited from movement in the first direction D1. When thesecond stop portion 482 of one stop block 48 touches the second stop 422of the respective first rail 42, the guide rods 46 and the sliding plate50 are prohibited from movement in the second direction D2.

Although particular embodiments of the invention have been described indetail for purposes of illustration, various modifications andenhancements may be made without departing from the spirit and scope ofthe invention. Accordingly, the invention is not to be limited except asby the appended claims.

1. A worktable comprising: a base having a top wall; a least one firstrail fixedly mounted on the top wall of said base, said at least onefirst rail each having a guide groove, a first stop and a second stop; aleast one guide rod respectively received in the guide groove of each ofsaid at least one first rail and alternatively movable in a firstdirection and a second direction reversed to the first direction, saidat least one guide rod each having a first end and a second end; a firstend strip fixedly fastened to the first end of each of said at least oneguide rod for stopping said at least one guide rod from movement in saidfirst direction when said first end strip contacts the first stop ofeach of said at least one first rail; a second end strip fixedlyfastened to the second end of each of said at least one guide rod forstopping said at least one guide rod from movement in said seconddirection when said second end strip contacts the second stop of each ofsaid at least one first rail a sliding plate slidably supported on saidat least one guide rod, said sliding plate having a bottom wall; and atleast one second rail fixedly mounted on the bottom wall of said slidingplate, said at least one second rail having a guide groove, whichreceives one of said at least one guide rod, a first push portion, whichenables said at least one guide rod to be moved in said first directionwhen touching said second end strip, and a second push portion, whichenables said at least one guide rod to be moved in said second directionwhen touching said first end strip; wherein said at least one first raileach is formed of one single solid bar, which has a first end formingthe first stop of the respective first rail and a second end forming thesecond stop of the respective first rail, the guide groove of each ofsaid at least one first rail extending along the length of therespective single solid bar.